The present invention relates to an arrangement for heating and/or heat retaining of containers and their contents, for example ladles to be filled with molten metal. More particularly, it relates to an arrangement of this type which has an air-fuel mixture burner directed toward the interior of the container, a cover for a container opening, and a preheating device for combustion air.
Arrangements of this type are known in the art. The cover for the container opening is composed usually of a plate which is lined at its side facing the container interior with a refractory material. The burner is located in the center of this plate. The smoke gas generated during combustion escapes through the annular gap between the container opening and the cover plate. In addition to strong air contamination and heating and connected therewith poor working conditions, such an arrangement is not satisfactory in the sense of energy consumption. Since the container which accommodates the molten metal has a relatively thick refractory lining which possesses a considerable heat-accumulating capacity, the refractory lining must be supplied before filling of the metal into the container with a considerable quantity of heat energy so as to prevent strong cooling of the molten metal as a result of the temperature equalization between the refractory lining and metal. In correspondence with this, low efficiency and considerable energy loss take place in the heating arrangement.
From the field of furnaces it has been known to use recuperators into which the thermal energy of the waste gases is used to supply it to the combustion air and thereby to increase the efficiency of the installation. Such recuperators are mainly placed separately from the furnace, and therefore it is necessary to provide between the furnace and the recuperator expensive pipe conduits for transporting the waste gas and air. Such installations are not only expensive, but also do not provide a very high efficiency, since heat losses take place through the pipe conduits between the furnace and the recuperator.
Burners with small output are also known in which the waste gas is used directly for preheating the combustion air. These arrangements are, however, connected with certain conditions in the sense of control and construction. In burners of greater output, the direct preheating of the combustion air by the waste gas has not been utilized.